using System;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Security.AccessControl;
using System.Security.Cryptography;
using System.Security.Principal;
using System.Threading;
using System.Windows.Forms;
using System.Xml.Linq;
using System.Drawing;
using System.Linq;
using System.Xml;
using System.IO.Compression;

namespace UpTool2
{
    static class Program
    {
        public static Form splash;
        public static bool online;
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            ShowSplash();
            string appGuid = ((GuidAttribute)Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(GuidAttribute), false).GetValue(0)).Value.ToString();
            string mutexId = string.Format("Global\\{{{0}}}", appGuid);
            var allowEveryoneRule = new MutexAccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MutexRights.FullControl, AccessControlType.Allow);
            var securitySettings = new MutexSecurity();
            securitySettings.AddAccessRule(allowEveryoneRule);
            using (var mutex = new Mutex(false, mutexId, out bool createdNew, securitySettings))
            {
                var hasHandle = false;
#if !DEBUG
                try
                {
#endif
                    try
                    {
                        hasHandle = mutex.WaitOne(5000, false);
                        if (hasHandle == false)
                            throw new TimeoutException("Timeout waiting for exclusive access");
                    }
                    catch (AbandonedMutexException)
                    {
#if DEBUG
                        Console.WriteLine("Mutex abandoned");
#endif
                        hasHandle = true;
                    }
                    if (!Directory.Exists(GlobalVariables.dir + @"\Apps"))
                        Directory.CreateDirectory(GlobalVariables.dir + @"\Apps");
                    string xml = GlobalVariables.dir + @"\info.xml";
                    FixXML(xml);
                    string metaXML = XDocument.Load(xml).Element("meta").Element("UpdateSource").Value;
                    online = Ping(metaXML);
                    if (!online || UpdateCheck(GlobalVariables.dir, xml, metaXML))
                        Application.Run(new MainForm());
#if !DEBUG
                }
                catch (Exception e1)
                {
                    MessageBox.Show(e1.ToString());
                }
                finally
                {
                    if (hasHandle)
                        mutex.ReleaseMutex();
                }
#endif
            }
        }

        static void ShowSplash()
        {
            splash = new Form
            {
                StartPosition = FormStartPosition.CenterScreen,
                FormBorderStyle = FormBorderStyle.None,
                ControlBox = false,
                MaximizeBox = false,
                MinimizeBox = false,
                ShowIcon = false,
                ShowInTaskbar = false,
                Size = new Size(700, 400),
                ForeColor = Color.Green,
                TopMost = true
            };
            splash.MaximumSize = splash.Size;
            splash.MinimumSize = splash.Size;
            Label splashL = new Label
            {
                AutoSize = false,
                Dock = DockStyle.Fill,
                TextAlign = ContentAlignment.MiddleCenter,
                Text = "Loading",
                Font = new Font(FontFamily.GenericSansSerif, 40)
            };
            splash.Controls.Add(splashL);
            splash.Show();
            splash.BringToFront();
        }

        static void FixXML(string xml)
        {
            try
            {
                if ((!File.Exists(xml)) || XDocument.Load(xml).Element("meta") == null)
                    new XElement("meta", new XElement("Version", 0), new XElement("UpdateSource", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Meta.xml"), new XElement("Repos", new XElement("Repo", new XElement("Name", "UpTool2 official Repo"), new XElement("Link", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Repo.xml"))), new XElement("LocalRepo")).Save(xml);
                else
                {
                    XDocument x = XDocument.Load(xml);
                    XElement meta = x.Element("meta");
                    if (XDocument.Load(xml).Element("meta").Element("Version") == null)
                        meta.Add(new XElement("Version", 0));
                    if (XDocument.Load(xml).Element("meta").Element("UpdateSource") == null)
                        meta.Add(new XElement("UpdateSource", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Meta.xml"));
                    if (XDocument.Load(xml).Element("meta").Element("Repos") == null)
                        meta.Add(new XElement("Repos", new XElement("Repo", new XElement("Name", "UpTool2 official Repo"), new XElement("Link", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Repo.xml"))));
                    else if (XDocument.Load(xml).Element("meta").Element("Repos").Elements("Repo").Count() == 0)
                        meta.Element("Repos").Add(new XElement("Repo", new XElement("Name", "UpTool2 official Repo"), new XElement("Link", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Repo.xml")));
                    else
                        meta.Element("Repos").Elements("Repo").Select(s => s.Element("Link"))
                            .Where(s => s.Value == "https://github.com/CreepyCrafter24/UpTool2/releases/download/Repo/Repo.xml")
                            .ToList().ForEach(s => s.Value = "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Repo.xml");
                    if (XDocument.Load(xml).Element("meta").Element("LocalRepo") == null)
                        meta.Add(new XElement("LocalRepo"));
                    x.Save(xml);
                }
            }
            catch (XmlException)
            {
                new XElement("meta", new XElement("Version", 0), new XElement("Repos", new XElement("Repo", new XElement("Name", "UpTool2 official Repo"), new XElement("Link", "https://raw.githubusercontent.com/CreepyCrafter24/UpTool2/master/Repo.xml"))), new XElement("LocalRepo")).Save(xml);
            }
        }

        static bool UpdateCheck(string dir, string xml, string metaXML)
        {
            XElement meta = XDocument.Load(metaXML).Element("meta");
            bool updatable;
            string ver = meta.Element("Version").Value;
            if (int.TryParse(ver, out int version))
                updatable = int.Parse(XDocument.Load(xml).Element("meta").Element("Version").Value) < version;
            else
                updatable = Assembly.GetExecutingAssembly().GetName().Version < Version.Parse(ver);
            if (updatable)
            {
                using (DownloadDialog dlg = new DownloadDialog(meta.Element("File").Value, dir + @"\update.tmp"))
                {
                    if (dlg.ShowDialog() != DialogResult.OK)
                        throw new Exception("Failed to update");
                }
                using (SHA256CryptoServiceProvider sha256 = new SHA256CryptoServiceProvider())
                {
                    string pkghash = BitConverter.ToString(sha256.ComputeHash(File.ReadAllBytes(dir + @"\update.tmp"))).Replace("-", string.Empty).ToUpper();
                    if (pkghash != meta.Element("Hash").Value.ToUpper())
                        throw new Exception("The hash is not equal to the one stored in the repo:\r\nPackage: " + pkghash + "\r\nOnline: " + meta.Element("Hash").Value.ToUpper());
                }
                if (File.Exists(dir + @"\update.exe"))
                    File.Delete(dir + @"\update.exe");
                try
                {
                    //Try extracting. This is done to support automatically built updates
                    if (Directory.Exists(dir + @"\update"))
                        Directory.Delete(dir + @"\update", true);
                    ZipFile.ExtractToDirectory(dir + @"\update.tmp", dir + @"\update");
                    File.Delete(dir + @"\update.tmp");
                    string[] array = Directory.GetFiles(dir + @"\update\Release");
                    for (int i = 0; i < array.Length; i++)
                        File.Copy(array[i], dir + @"\update.exe", true);
                }
                catch (InvalidDataException)
                {
                    //If it can not be extracted as a .zip we try reading to see if it is a binary by trying to read it's name
                    AssemblyName.GetAssemblyName(dir + @"\update.tmp");
                    File.Move(dir + @"\update.tmp", dir + @"\update.exe");
                }
                new XElement("meta", new XElement("Version", ver)).Save(xml);
                splash.Hide();
                Process.Start(new ProcessStartInfo { FileName = "cmd.exe", Arguments = "/C timeout /t 2 & copy /b/v/y \"" + dir + @"\update.exe" + "\" \"" + Application.ExecutablePath + "\" & \"" + Application.ExecutablePath + "\"", CreateNoWindow = true, WindowStyle = ProcessWindowStyle.Hidden });
                return false;
            }
            return true;
        }

        public static bool Ping(string url)
        {
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.Timeout = 3000;
                request.AllowAutoRedirect = false;
                request.Method = "HEAD";

                using (var response = request.GetResponse())
                {
                    return true;
                }
            }
            catch
            {
                return false;
            }
        }
    }
}